A Wexelblat disaster is a disaster caused by the interaction of natural phenomena with human technology. Specifically, it refers to a class of disasters occurring because humans build systems to human scale that affect the planet and climate, which operate at very different scales. A natural event damages some technological device or installation, and its failure precipitates much greater harm than the initial event. For instance, a storm may cause an oil tanker to sink, causing oil to spill out, causing massive damage to marine and coastal ecosystems. Wexelblat disasters are infrastructural in nature, rather than merely external. They are collapse, implosion, and failure type events, rather than explosive, razing type events. An example is extensive flooding in New Orleans following Hurricane Katrina's damage to that city's levees.

Wexelblat disasters are named after Alan Wexelblat, a graduate of the MIT Media Lab. The original coinage, offered by Wexelblat himself, was "Viridian Disaster", in reference to the Viridian Design Movement led by Bruce Sterling, a science fiction writer, futurist, and activist who has focused his non-fiction writings since the mid-1990s (as well as at least one novel) on what was first called the greenhouse effect and is now more commonly called global warming or man-made climate change.

Bruce Sterling for a while used structures such as " Wexelblat-style Viridian Disaster" , but eventually shifted to "Wexelblat Disaster", and that coinage subsequently entered broader use. The concept and some explanation are also used in a book on the Katrina hurricane disaster in New Orleans . Wexelblat himself is somewhat chagrined by the association of his family name with a class of disasters.